1. Technical Field
The present disclosure relates to a method for measuring dispersion in an optical fiber. More particularly, the present disclosure relates to a method of using a periodic wavelength variation pulse light signal to measure dispersion in an optical fiber.
2. Description of Related Art
Conventionally, dispersion or group velocity dispersion (GVD) would cause a group velocity of the light to have different pulse time delays due to the light having different wavelengths when the light propagates in a transmission medium (e.g. optical fiber) having none-zero dispersion value. In other words, during the light propagation inside a dispersive fiber, the light pulse may broaden due to the fiber dispersion effect in the transmission medium. Thus, for the optical fiber communication applications, the group velocity dispersion will cause neighboring signals to overlap with each other, thus limiting the maximum data transmission speed. Therefore, how the dispersion in the optical fiber can be measured such that it can be compensated or applied is an essential issue.
In prior art, there are some methods for measuring the group velocity dispersion, such as time of flight (TOF) technique, temporal interferometry technique, spectrum interferometry technique, phase-shift modulation (MPS) technique, and so on. However, the foregoing methods are usually restricted by response time of detectors, disturbance of circumstances, modulating frequency of modulators or measuring sensitivity, thus the group velocity dispersion cannot be measured more accurately by inexpensive measuring apparatuses.